The speaker's wife, Sally Bercow, later tweeted "It's news to us all!". She said she was not going to Afghanistan and neither, to her knowledge, was her husband.

The moves to increase inter-parliamentary co-operation come amid concern in the British government at recent efforts by the Afghan president, Hamid Karzai, to overturn the results of 25% of Afghanistan's parliamentary elections, which has further inflamed international concern about democratic progress in Afghanistan.

Cameron raised the matter with Karzai in his bilateral meeting on Tuesday morning.

Cameron had reminded journalists on Monday that his aspirations for Afghanistan were even more modest than previous prime ministers, telling a gathering of US and UK troops that they were not fighting to "create a perfect democracy" nor "create a perfect country" but to build up the Afghan troops so that they could take the reins themselves.

Speaking in Kabul, Cameron said he had raised the issue of the relationship between the Afghan "executive and parliament".

In June, Karzai set up a special court, which overturned the results in a quarter of parliamentary seats from last year's elections, effectively making null and void 62 MPs' results.